In various earlier post I presented mazes which are made more difficult because different objects are moving at the same time, constrained by specific rules. Movin’ Maze 3D (and the free version Movin’ Maze 3D Lite) presents yet another variation on this theme (a screenshot is shown to the right here). It is a nicely made puzzle, though there are so many options and possibilities that the puzzling aspect is a bit lost in the joyful chaos.

Robert Abbott’s Theseus and the Minotaur is one of the puzzles on the app store with more depth (see my earlier post for more details). In 2002 the game was cloned by PopCap for their online game Mummy Maze (shown here to the right). This game explicitly credits Robert Abbott, although this did not happen automatically (see this post for more details on that history). Yet, PopCap actually did add some new aspects to the puzzle. Those new additions are now cloned by a new iPhone game, though without any credit (once again).

Four cardboard pieces were included in a box of White Rose Ceylon Tea distributed by Seeman Brothers of New York in 1903. On one of the pieces was written: “Arrange these four pieces of cardboard so as to form a perfect T. White Rose Ceylon is a perfect Tea.” This puzzle has been copied many times, mostly simply known as T-puzzle. When you see the solution (shown here to the right), then this puzzle seems obviously simple. However, when you are given the pieces disassembled, then the assembly appears to be really hard.

Among the large class of Put Together puzzles, there is a subclass of puzzle that can be technically classified as non-interlocking 2D assembly puzzles. Probably the most well-known puzzle of this kind is Tangram, but there are very many different kinds of puzzles, also in the app store. The principle of such puzzles is that pieces have to assembled to form a particular configuration. This is just like jig-saw puzzles, though those are typically interlocking.

In an earlier post I introduced movement-until-blocked puzzles. The idea of such puzzles is that there are various objects to be moved towards a goal. Each object can be moved separately, and in any direction possible. However, the catch is that the movement will continue until it is blocked by a wall or another moveable object. In that earlier post and the follow-up I presented six different iPhone puzzles that used this principle. In the meantime two more have become available: Atomix and D-Star. Both are remakes of earlier games known under the same names.

In my earlier post on Vexed I mentioned the Vexed-clone by the korean developer Kim Byung Kwon. I was highly critical of that app because Kim did not refer to the GNU-license of the original game by James McCombe. Now, it turns out (as discussed in the comments to that post) that James McCombe was possibly not the true originator of that puzzle anyway.

However, Kim did it again, though this time with sliding block puzzles! He simply copied some of the best sliding block puzzles from Nick Baxter’s Sliding Block Page and now sells them for one dollar as Sliding Puzzle (iTunes link), without any mention of the originators! Let me rectify this at least here: the puzzles shown on the screenshot in iTunes are by Junichi Yananose, Serhiy Grabarchuk, Minoru Abe, and Ed Pegg Jr.

Kim’s webpage is difficult to decifer (neither my nor google’s knowledge of Korean is sufficient to really make sense of this page). If somebody know how to contact this person, please let me know. I find this unacceptable.

FissionQuest (and its lite version FissionQuest Lite) present another take on Sokoban-like puzzles (see my earlier posts on such puzzles). This game is like Sokoban in 3D, though you also have to watch out not to fall down to death.

An interesting puzzle concept is available in iEscape, iEscape LITE, and RabbitEscape (the last one is shown here to the right). They are all from the same developer, and basically just different packages around the same puzzle concept. The puzzles are closely related to Sokoban (see my earlier post on classic Sokoban ports for the iPhone). The difference to Sokoban is, in a nutshell, that the “blocks” to be pushed around are now placed in the edges of the graph, instead of on the vertices. So, one could call this “Sokoban on the edge”-puzzles.

Very many interesting games and puzzle concepts are being developed by the flash-gaming community. An example of such an interesting puzzle is Nodes, developed by Eggy (Bradley Erkelens) with the assistance some not further clarified person named Frank. The goal of the puzzle is to position the nodes of a graph in such a way that the vertices cross through a set of small circles. This game is also available on the iPhone, though unfortunately not through Eggy, nor with his consent.

In my previous post I discussed puzzles in which objects have to be guided to a goal by using various forms of reflection. All those puzzles attempted (with more or less success) to present a realistic physical environment. In this post I will present another class of puzzles that also is based on reflection, but implemented in a more abstract manner. In these games reflection is only possible in right angles, and the puzzle consists of placing diagonally oriented mirrors in such a way that an object (balls, or a beam of light) will be guided to the goal (or goals).

The following puzzles in the app store implement this approach (links redirect to iTunes):

There are various puzzles in the app store that provide a realistic replication of physical reality and use gravity, momentum or friction to make puzzles (as discussed in an earlier post). Another physical phenomenon that lends itself to design interesting puzzles is reflection. Three puzzle games in the app store (try to) realistically represent reflection, and make nice puzzles in that surrounding.

In the 1990s, Sierra Entertainment developed a series of educational computer games called “Dr. Brain” (indeed, Dr. Kawashima was not the first one to use his doctoral title to sell edutainment). In the third installment of the series from 1994, called The lost mind of Dr. Brain, a puzzle called “Motor Programming” was introduced, apparently inspired by the Logo programming language. The goal is to guide the dog Rathbone towards a brain (Dr. Brain’s brain) by using simple instructions like ‘forward’, ‘turn left’, etcetera. In this game’s simplistic programming language there are no loops nor recursion, only subroutines. The challenge of the puzzle is that only a limited number of instructions are allowed, and only two subroutines (also with a limited number of instructions each).

This puzzle has now also reached the iPhone, in different guises, and through a twisted path of attribution and inspiration.

The three games to be discussed in this post present in my opinion the most interesting game-developments on the iPhone. They are not puzzles in the strict sense as I tend to define it, because they all require a certain amount of dexterity. However, the balance between strategic planning and dexterous maneuvering is well thought through. You won’t solve these with only dexterity! Further, all these games are extremely well made, both visually and auditory. And they are all based on a very refined physical quasi-world, as I have discussed in my previous post. Interestingly, they all take a slightly different approach to which aspect of physics is highlighted: gravity, momentum, and friction.

Are you curious? The games I am referring to are the following (links redirect to iTunes):

In the development of computer games, one of the most important underlying developments is the refinement of the so-called physics engine. Originally, each developer would independently define all reactions of the program to each input of the user. Obviously, this is very labour-intensive, so already from the start of computer-games different solutions were developed. The basic idea is to frame the game into the surrounding of a quasi-reality, so that the game itself can figure out how to react. In this approach, the central problem was to build a suitable quasi-reality. However, the big profit was that the quasi-reality became to some extent independent of the game itself, so it could be reused. Eventually, the development of such quasi-realities (or physics engines as they are usually called) became an industry of its own (see the historical survey by Calen Henry and Jacob Karsemeyer for an in-depth analysis).

Most games using such engines are shoot and race games, but there are also various puzzles that use the power of a quasi-reality.

In 2005 a mathematics student called Mary Radcliffe developed the concept of a puzzle she called Planarity. It was implemented as a computer game on the internet by John Tantalo. The idea is to take an undirected graph, and the puzzle is to place the vertices (‘nodes’) in such a way that the graph is planar, i.e. the the edges (‘lines’) do not cross. A graph (drawn in 2D) without crossing edges is called a planar graph in mathematics, and this suggested name Planarity. It is an old problem in mathematics how to quickly determine whether a graph is planer or not.

The game became somewhat of a craze among the flash-based gaming community under the name Untangle (just google for “untangle game” and you will find dozens of implementations). Unexpectedly, the game is also available on the iPhone.

Things are moving ridiculously fast in the app store—I hardly can keep up with all the new puzzles becoming available every day! You might have noted that I keep adding updates to previous post when new apps arrive that simply replicate other puzzles (see for example my post on Rush Hour or Lights Out), or when previously criticized omission are added in updates (see for example my posts on Mouse House or Blocked). However, sometimes I will write a new post, when there is too much significantly new that has become available.

In this post I will revisit the topic of puzzles games that are similar in gameplay to one of those dinosaurs of computer games: Chip’s Challenge (for background, see my previous post on such games).

With this post, I will finally finish off the sequential removal puzzles, as far as I have found them in the app store (see all posts in this category). In a sequential removal puzzle, objects have to be removed according to some rules. By taking the wrong order of actions, you might end up in a dead end, so sequential removal puzzles can be seen as an abstract kind of maze (see my earlier primer on maze puzzles explaining this in more depth).

In real-life physical puzzles, sequential removal puzzles are not so widespread, because it is difficult to find interesting rules for removal that are transparently executable while manipulating objects on a board. Peg jump is possibly the only physical sequential removal puzzle. In contrast, for computer games the principle of sequential removal is very widespread, because even rather unwieldily rules of removal can be easily implemented for a computer to consistently perform. No cheating or accidental errors can occur. Because the goal of removing things, viz. clearing the board, is so intuitively simple, many computer games use this principle (just look at the dozens of Bejeweled-like games in the app store). The differentiation between such games lies in the details of the rules of removal. Enter the twisted rules of TurtleFlip!

The app FLIP is a combination of a Bejeweled-like match-three game, a tilt maze and a match-and-vanish puzzle. So in principle, there are many very interesting puzzle concepts combined into one neat little package. However, the execution leaves much to be desired, and the level-design is not very challenging. So, I really cannot recommend this app just now, but I will keep an eye on any updates.

Finally somebody reconsidered Peg Jump. The app Hiqup [link redirects to iTunes] is a sequential removal puzzle in which pieces are basically removed by jumping over them. So far nothing new. However, developer Moopf introduced various new twists into this classic puzzle principle, which make it an interesting puzzle-app, well worth the (low) price.

In a sequential removal puzzle pieces have to be removed in a sequence. Doing it in the wrong order will lead to a dead end. Lights Out is also a puzzle in which something has to be removed (all lights have to be turned off), and as a user you will perform actions sequentially. However, it turns out after some more pondering over the solutions that the order of actions is not important. So, strictly speaking this is not a sequential removal puzzle, but it definitively feels like one.